347 research outputs found
On-Site and External Energy Harvesting in Underground Wireless
Energy efficiency is vital for uninterrupted long-term operation of wireless underground communication nodes in the field of decision agriculture. In this paper, energy harvesting and wireless power transfer techniques are discussed with applications in underground wireless communications (UWC). Various external wireless power transfer techniques are explored. Moreover, key energy harvesting technologies are presented that utilize available energy sources in the field such as vibration, solar, and wind. In this regard, the Electromagnetic(EM)- and Magnetic Induction(MI)-based approaches are explained. Furthermore, the vibration-based energy harvesting models are reviewed as well. These energy harvesting approaches lead to design of an efficient wireless underground communication system to power underground nodes for prolonged field operation in decision agriculture
An Energy-Efficient Controller for Wirelessly-Powered Communication Networks
In a wirelessly-powered communication network (WPCN), an energy access point
(E-AP) supplies the energy needs of the network nodes through radio frequency
wave transmission, and the nodes store their received energy in their batteries
for possible data transmission. In this paper, we propose an online control
policy for energy transfer from the E-AP to the wireless nodes and for data
transfer among the nodes. With our proposed control policy, all data queues of
the nodes are stable, while the average energy consumption of the network is
shown to be within a bounded gap of the minimum energy required for stabilizing
the network. Our proposed policy is designed using a quadratic Lyapunov
function to capture the limitations on the energy consumption of the nodes
imposed by their battery levels. We show that under the proposed control
policy, the backlog level in the data queues and the stored energy level in the
batteries fluctuate in small intervals around some constant levels.
Consequently, by imposing negligible average data drop rate, the data buffer
size and the battery capacity of the nodes can be significantly reduced
Power Beacon’s deployment optimization for wirelessly powering massive Internet of Things networks
Abstract. The fifth-generation (5G) and beyond wireless cellular networks promise the native support to, among other use cases, the so-called Internet of Things (IoT). Different from human-based cellular services, IoT networks implement a novel vision where ordinary machines possess the ability to autonomously sense, actuate, compute, and communicate throughout the Internet. However, as the number of connected devices grows larger, an urgent demand for energy-efficient communication technologies arises. A key challenge related to IoT devices is that their very small form factor allows them to carry just a tiny battery that might not be even possible to replace due to installation conditions, or too costly in terms of maintenance because of the massiveness of the network. This issue limits the lifetime of the network and compromises its reliability.
Wireless energy transfer (WET) has emerged as a potential candidate to replenish sensors’ batteries or to sustain the operation of battery-free devices, as it provides a controllable source of energy over-the-air. Therefore, WET eliminates the need for regular maintenance, allows sensors’ form factor reduction, and reduces the battery disposal that contributes to the environment pollution.
In this thesis, we review some WET-enabled scenarios and state-of-the-art techniques for implementing WET in IoT networks. In particular, we focus our attention on the deployment optimization of the so-called power beacons (PBs), which are the energy transmitters for charging a massive IoT deployment subject to a network-wide probabilistic energy outage constraint. We assume that IoT sensors’ positions are unknown at the PBs, and hence we maximize the average incident power on the worst network location. We propose a linear-time complexity algorithm for optimizing the PBs’ positions that outperforms benchmark methods in terms of minimum average incident power and computation time. Then, we also present some insights on the maximum coverage area under certain propagation conditions
Power Beacon-Assisted Millimeter Wave Ad Hoc Networks
Deployment of low cost power beacons (PBs) is a promising solution for
dedicated wireless power transfer (WPT) in future wireless networks. In this
paper, we present a tractable model for PB-assisted millimeter wave (mmWave)
wireless ad hoc networks, where each transmitter (TX) harvests energy from all
PBs and then uses the harvested energy to transmit information to its desired
receiver. Our model accounts for realistic aspects of WPT and mmWave
transmissions, such as power circuit activation threshold, allowed maximum
harvested power, maximum transmit power, beamforming and blockage. Using
stochastic geometry, we obtain the Laplace transform of the aggregate received
power at the TX to calculate the power coverage probability. We approximate and
discretize the transmit power of each TX into a finite number of discrete power
levels in log scale to compute the channel and total coverage probability. We
compare our analytical predictions to simulations and observe good accuracy.
The proposed model allows insights into effect of system parameters, such as
transmit power of PBs, PB density, main lobe beam-width and power circuit
activation threshold on the overall coverage probability. The results confirm
that it is feasible and safe to power TXs in a mmWave ad hoc network using PBs.Comment: This work has been submitted to the IEEE for possible publication.
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Fundamentals of Wireless Information and Power Transfer: From RF Energy Harvester Models to Signal and System Designs
Radio waves carry both energy and information simultaneously. Nevertheless,
Radio-Frequency (RF) transmission of these quantities have traditionally been
treated separately. Currently, we are experiencing a paradigm shift in wireless
network design, namely unifying wireless transmission of information and power
so as to make the best use of the RF spectrum and radiations as well as the
network infrastructure for the dual purpose of communicating and energizing. In
this paper, we review and discuss recent progress on laying the foundations of
the envisioned dual purpose networks by establishing a signal theory and design
for Wireless Information and Power Transmission (WIPT) and identifying the
fundamental tradeoff between conveying information and power wirelessly. We
start with an overview of WIPT challenges and technologies, namely Simultaneous
Wireless Information and Power Transfer (SWIPT),Wirelessly Powered
Communication Network (WPCN), and Wirelessly Powered Backscatter Communication
(WPBC). We then characterize energy harvesters and show how WIPT signal and
system designs crucially revolve around the underlying energy harvester model.
To that end, we highlight three different energy harvester models, namely one
linear model and two nonlinear models, and show how WIPT designs differ for
each of them in single-user and multi-user deployments. Topics discussed
include rate-energy region characterization, transmitter and receiver
architecture, waveform design, modulation, beamforming and input distribution
optimizations, resource allocation, and RF spectrum use. We discuss and check
the validity of the different energy harvester models and the resulting signal
theory and design based on circuit simulations, prototyping and
experimentation. We also point out numerous directions that are promising for
future research.Comment: guest editor-authored tutorial paper submitted to IEEE JSAC special
issue on wireless transmission of information and powe
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